Method and apparatus for making radiographic diaphragm



A. J. KliAu METHOD AND APPARATUS FOR MAKING RADIOGRAPHIC DIAPHRAGM Filed June 18, 1951 2 Sheets-g FIG.4

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METHOD AND APPARATUS FOR MAKING RADIOGRAPHIC DIAPHRAGM Filed June 18, 1951 2 Sheets-Sheet 2 I INVENTOR.' ARTHUR J. KIZAUR United States Patenffi 2,696,634 Patented Dec. 14, 1954 ice METHOD AND APPARATUS FOR MAKING RADIOGRAPHIC DIAPHRAGM Arthur :J; I Kizaury Wauwatdsa; Wis, assignor' to' General Electric Company, a corporation-= New York Th'e,;p r.esent invention rela'tesin general .to; radiography, thatnis to .say,, the artof makingX ray: photographs, and has more; particular reference .to .anirnproved .radio- I graphicdiaphragrnpf .Ih'esont commonly designated as raw Bucky diaphragmnandusedin'rradiography to improves picture definition, th(e:;inYeution.including l improved zap; paratus and proceduresio'r. making them diaphragm The function ofBjucky type diaphragmsrand thevmeth od w of'using thersame in radiography are wellvknownm Such/a diaphragms comprise, alternatehgr id. .strips toff lead .or other substance opaque to X-rays,.and strips of wood or other--'X-ray ,transparent, material tthe strips being ar-w ranged-to form a 'composite'plate ordiaphragm which; the strips extend ztransversely' jOfIhe diaphragm and-.ar.e angulated so asftopermitonly rays emanating .directly, froma primary source"'of:'"X-rays to pass thtoughlthe. diaphragm; whileabsorbing and thus excluding; from the ;ray -sensitive material"being; exposed. all "indirect, sec-; ondary; reflected '-orincidental'frays originating fromfl. other than the primary-"source Radiographic dia'phragmsof the 'sort heretofore provided are relatively-costly-,qdue'to'the diflicultiesof arranging the'exceedingly'fine gauge metalstrips in spaced relationshipandaccurately angula'ted"in-the"gridf'strue ture; and much efforthasheretofore been expanded'iiin seeking-:rneans. for reducing the=:cost"of making dian phragtns, while at the-same time improvingtheprecision of strip angulation. and= preserving'therindividual fine gauge; strip :material 1 in -fiat,- unbuckled condition -,inthe struc'-: ture, the U. SLPatent No.2,115,755,- which issued Mayf 3,' 1938, on the. invention of luli'us B. Wantz'and Arthur J.v Kizaur= describing zprevious-efiorts made toward 16-.'

ducing-the costrand-improvingthe-quality? of Bucky type? diaphragms.

An important: object ofthe present invention is--to" simplify and reducezthe cost of making Bu'ck'y typeradidgraphic screens by=providing for the assembly and angw lationrzof fine: gauge metal diaphragm strips-*and. theapplication of'vX-rayz transparent material ;thercb'etween;

as an continuously progressive procedure accomplished in" a direc-tionlengthwiseoft thet'strip's, .to thereby avoid the inaccuracies. and time consumption of the laborious," piece-meal: assembly operations heretofore considered necessary in producingl-diaphragms :of the character men-' tione Another importantqobject is' to provide for building radiographic .diaphragms v by first: fixing the -metal grid strips of :the :diaphragm'iin. paral-lel, ,spacedapart; and

relatively angulated=position as Lin a suitable jig, and

then applying rX-ray transparent: material in situ'between the positioned tstripsg a further object being tomaintain i the I metal igrid strips'under; slight; ztensionato assure thatthe same remain :inrfiat condition-duringithe application of i the .-X'-ray transparent-materiale. in "situ therebetween;

Another-important object vis toaemploy a plastioX ray transparent materialaiasqag-grid strip; spacingzmedium: in diaphragms {of the character, mentioned; a further object being a to provide for the i-tapphcation 'of :the transparentci material in fiuidwondition between .the'zstrips; .and. theref er to i y: hermateriabjin "situnbetween'tthe: grid strips;,- -.to therebwsuppertathe': samev inzaccurately' angua lated relations in the finished sqreemr ppbr ia $25 1 ans zforrholdmg diaphragm :gridtf'strips w zetozzprovide novelpl'stripra 2L; accurately in parallel, relatively angulated relationship? during the application; and solidifioationfiof--the -X-ray transparent material therebetween:

Another important object t is to provide means for: applying plastic 'materiala'in'efluid;form between thee: positioned! gridi-v strips and solidifyingqlthet material i in? situ-ttherebetween, prognessively in the longitudinal direc-r tid'n...of ;.the v strips "from one- .endwofl the: 1 grid :zstructure towardfthe other; ar/further 'object being; to provide a-- strip combing member movable. longitudinally, or the; strips during gth application off therX ray transparenba materiallgtherebetween, to maintain theastrips.vinmflat slightly'jtaunftand lac'curately' oriented and lspaced vconclia tion as'ithe 'rnaterialfiis'v applied; and", solidified therebe tweenw Another important 'obje'ct"is to provide screenr'fab'ri-I cating apparatus includingga .pantadapted =to. receive-ta predetermined quantityof-iplas'tic' IX y transparentima-i, terial 'in' fluid condition; and int'o which grid-estripsgsu portedinparallel'and relatively'angulated position, as agsuitable" jig'grnav;be'irnmersedtlsol that, by moving, stripptensioning, comblongitudinallypf vthe-siibfnergedi strips in; the pan, and'bysoliditying the fluid materialubeal hind th'e' comb, the diaphragm may be produced Lira final L form'yvithf the' grid strips thereofjfembedded "in the,- soliclified' mate'rialgla' flirtherl'objectzbeingjo provide a xilfary apparatus; byimean's of which the pan rand; its; contents'imav'be'moved 'from-a heating jzone, infwh'iehith'e transparent ma'terial 'is -'maintained" in fluid conditionst progressively irito a cooling zone for'theprogressive soli ficat-io'n of i the mat'eriallin situ' around fithe submerged" grid strips-in"th'e panyfromone-enclof"th'pad'toward its'--' other en'dj including means. for ."moving the strip comb inthe 'pan =in-'-th'edirectionuof th'efstripsand tin adVanceof-tlie solidifying material! 7 Anotherimportant' obje'ct-"is" toprovide an improved radiographic diaphragm comprising-preferably metal strips of X-tay opaque"material "in parallel and accurately? angulated positiori and embedded insolidified X- raytrans v parent plastic material; a"-f1irther "object being'to' provide 3' such a diaphragmas a flat plate 1having protective panels ofpreferably metallic' -X-"r ay transparent materialapplied f thereto',* in position 'coveringcthe" opposite faces'of the diaphragmiplatep'a *sti-ll further object being to provide an' redge tbin'di'ng 1 of suitable; preferably 'inetallic material comprisingia frame;-* in positi'on enclosing the 'edgesof the diaphragm'plate and of the protectivepanels to hold '-the"'- same togetherrasra runit.

Thi .eforgeoing ::and: numerous! other "important objectsfjadvantages," and "inherent functions 'ofltheinventionwill" become i apparent as :the same'fiis rmore' ful-ly 'unde'rst'ood frfomathe following edescliptidng .which taken in: cornea-- tiorn with-zthexaccomp anyin g :drawingsy discloses pr'eferred embodiments of f thex inventionz I Referring-10' theidrawings Fig.-;1 is. a :diagrarnmati lewvof 'radiographic equi mentnjnchldihg la"diaphragrn; embodying the .present' -in ventiony' i Fig- 2 is aperspectiveview of theaimproveddiaphragmy F ig.--;;3 is amenlarged2sectionalrvieww-takensubstantiallyf along theline'B-"Q in -Fig. 2;3 v

Fig. ,4 is a sectional-.- view taken :longitudinally athrough E equipment-;.for 1 making the" diaphragm? Figs S .andz fi are-sectional. views, respectively taken-nsubstantially-alongthe lines 5-5 Sand 66'-.-in 'Fig: -4;1--;

Fig.-.7 is a-sectional viewshowing a modified-"formt-ofl tray illustrated: in wv-Figs. 5 and-:6; f

Fig. ;8 :iS a perspective-:view showing; the --.-equi'prnent illustratediim Fig; 4 -in combina'ti'oni-withf auxiliary- "open-T ating-iequipmennr- Fig.1;9 .-is-*a ipers'pectiue' view Fshowing traction apparatns forzoperating thezauxilia'ry equipement illustratedin Fig? 8; 'and:

Fig. 10 isa schematic wiring-dia'g' fdr 'controlling' the-:operatiou of. the tract-idepparatus v To illustrate the:. inventio the-drawin'gsfshbva imFi l,' radio'graphic 'equip'inent comprising: a' 'suitable IX- source, such as an X-ray generating tube 11, having an anode 12 forming a substantially point source of an X-ray beam 13, a table 14 for the support of an object 15 to be radiographically pictured, a diaphragm 16 embodying the present invention, and a sheet or film of light sensitive material 17 disposed behind the diaphragm in position to receive an X-ray induced picture of the object 15.

In making radiographic pictures, the presence of objects such as particles or bodies 18, within the field of the useful X-ray beam 13 and capable of being excited by the beam to form secondary X-ray sources, will, in the absence of the diaphragm 16 cause fogging of the X-ray picture in the layer 17. Such fogging, of course, is the result of the action of secondary X-rays emanating from the source or sources 18, thereby impairing the clarity and definition of the resulting picture. Such fogging of the picture, as the result of excitation of secondary X-ray sources by action of the beam 13, may be eliminated by utilizing the screen 16, which is adapted to screen, from the layer 17, substantially all X-rays except those proceeding in a direction radially of the primary X-ray source 12.

To this end, the screen or diaphragm 16 comprises a plurality of laminations or strips 19 of X-ray opaque material, such as lead, the strips extending transversely of the diaphragm and being disposed in spaced apart relationship. The strips 19 are preferably separated and maintained in spaced relationship by material which is transparent to X-rays. In Bucky diaphragms of the sort heretofore provided the opaque grid strips have commonly been separated and held in desired spaced relationship by means of wooden spacing strips, the X-ray opaque grid strips and transparent spacing material being preferably arranged to form a fiat plate, in which each grid strip 19 is relatively angulated with respect to the others and lies in a plane passing substantially through the X-ray source 12 provided at the anode of the tube 11.

It will be seen that, if the screen 16 and the sensitive picturing material 17 are held stationary, during exposure of the material 17 to X-light from the source 12, the sensitive sheet 17 will receive a striped or striated image corresponding to the opaque grid strips 19. Since this striped image, comprising so-called'grid lines, is undesirable in an X-ray'picture because of interference with the diagnostic clarity of the pictured image of the obiect 15, means is commonly provided for relatively shifting the screen 16 with respect to the sensitive layer or film 17 during exposure. Ordinarily, the film 17 is preferably held stationary with respect to the object being pictured and the screen 16 is shifted between the ob ect 15 and the film, such movement being accomplished transversely, preferably at right angles, with respect to the longitudinal orientation of the grid strips 19 in the diaphragm or screen. By so moving the screen through a predetermined displacement at a predetermined, preferably uniform rate of speed, depending upon the exposure interval and the spacement of the grid strips 19 in the screen, the striated image of the grid strips may be eliminated in the resulting picture formed in the sheet or film 17.

The general construction of the so-called Bucky diaphragm was proposed by Gustav Bucky in U. S. Letters Patent No. 1,164,987, issued December 21, 1915; and the method of eliminating the striated image of the grid strips, by. moving the diaphragm or screen relatively with respect to the sensitive film during the exposure interval, was proposed in 1920 by Dr. Holles E. Potter. The Bucky diaphragm, when used in accordance with the technique developed by Dr. Potter, has been found satisfactory in making X-ray pictures where the exposure interval is in excess of five seconds. Improvements and refinements in the original Bucky diaphragm structure and in radiographic technique, including the improvements disclosed in U. S. Letters Patent No. 2,115,755, issued May 3, 1938, on the invention of Julius B. Wantz and Arthur I. Kizaur, and U. S. Letters Patent No. 2,435,823, issued February 10, 1948, on the invention of Glenn W. Files, now permit the production of satisfactory radiographic negatives. free of grid lines, during fractional second exposure intervals.

Among the difficulties encountered in building satisfactory Buckv type radiographic diaphragms is that which arises from the necessity of maintaining the grid strips 19 accurately in relatively angulated position and in flat 4 planar condition in the diaphragm. Any deviation of strip from the position which it is required to occupy for optimum radiographic results will introduce correspond ing defects in pictures made by X-ray exposure through the diaphragm. The grid strips have thickness of the order of 0.002 inches, and width of the order of Via- Mt inch, and they are spaced apart in the diaphragm distances of the order of 0.015 inches, it being desirable to make the strips as wide as possible and as thin as possi ble in the interests of improved picture definition. Radiographic diaphragms also are currently made in square sizes as large as l8 inches, that is to say, square diaphragms having an area of the order of 300 square inches and up, in which the length of the grid strips is of the order of 18 inches, such size being commonly considered to be the practical limit because of the difiiculty of maintaining longer and Wider strips in accurately oriented and angulated position in the diaphragm structure, such difficulties being augmented by the exceedingly thin, foil like character of the strip material. I

In view of the foregoing difiiculties, it has heretofore been the practice to build up radiographic diaphragms by alternately laminating metal foil with layers of X-ray transparent material, such as wood, to form a laminated stack, then cutting laminated blocks of strip-like character from such stack, squeezing the blocks in order to differentially compress the somewhat resilient wooden material thereof so as approximately to angulate the metal grid strips, and finally assembling a series of the strip-like blocks and securing the same together to form the diaphragm. Such a procedure is not only slow, time consuming, costly and laborious, but the grid strips in the resulting screen are only approximately disposed in the required optimum positions of relative angulation. Furthermore, the necessary squeezing operation, to some extent at least, distorts the grid strips, as by bending or buckling the same, and useful results are attained only by carefully selecting X-ray transparent grid spacing ma-* terial for its uniform squeezing characteristics in the interests of strip angulation accuracy. In addition, the natural resilience of the squeezed spacing material tends to return the parts to normal unsqueezed condition, thereby tending to displace the grid strips from the desired angulated position in the screen, and also to buckle the screen itself.

The present invention provides for the production of Bucky type radiographic diaphragms in which the grid strips are accurately positioned and angulated, and are maintained in flat, accurately oriented, planar position in the screen. The present invention also provides for the fabrication of diaphragms comprising angulated strips and intervening X-ray transparent spacing material as a single, continuous, and substantially automatic operation, thereby eliminating the several laborious steps heretofore required in producing the diaphragm portion of the screen.

To these ends, means comprising a mounting jig 20 may be provided for holding a plurality of grid strips 19 in properly spaced, angulated position, the jig preferably comprising end bars 21 disposed in parallel, spaced relation, and spacing bars 22 detachably secured to the end bars in position extending therebetween for :the purpose of securing the bars in spaced, preferably parallel relationship. The spacing bars 22 are preferably secured in readily detachable fashion to the end bars, as by means of screws 23 or other suitable fastening devices, each bar 22 preferably extending between corresponding ends of the end bars 21 to constitute the struc ture as a preferably rectangular frame, in which the end bars form the opposite ends of the frame.

As shown, the end bars preferably comprise plates having dependent lower edges, the plates being formed with slots 24 opening at the lower edges of the plates and spaced apart and angulated therein to correspond with the desired grid strip angulation and position in the finished. grid structure. Accordingly, the grid strips 19 may be assembled, as by hand operation, on the frame or jig 20 in the same relative position to be occupied by the strips in the grid structure, such assembly merely comprising the application. of each strip with its opposite ends extending in corresponding slots 24 of the end members 21, said slots being sized to snugly receive and frictionally engage the ends of the grid strips. If desired, each end member may be relieved, as at 25,

to provide a space into which may be bent or folded the extremeties of the strips, which extend outwardly on the wheels 41 and drivingly connected,as at 44, with the opposite ends of the carriage 37. Accordingly, by driving the shafts 40 in one direction or the other, the carriage frame 37 may be moved from the liquid condition zone 34 into the solid condition zone 35 at a desired rate of speed, and may be returned from the zone 35 to the zone 34. It is desirable to provide for moving the carriage frame 37 at an extremely slow speed from the zone 34 into the zone 35, in order to accommodate the relatively slow rate of solidification of the spacing medium behind the comb member 26. At the conclusion of the projecting movement of the carriage frame into the zone 35, the pan and its contents, with the spacing medium in substantially solid condition, may be immediately removed from the carriage frame and set aside for further solidification of the spacing medium, including any desirable or necessary medium curing procedures.

After removal of the tray and its contents from the carriage frame, it is, of course, desirable to provide for the prompt return of the carriage frame to the zone 34 to receive a succeeding tray and contents for a repetition of the screen fabricating procedure. To this end, the traction means 39 may be driven, as by a preferably electric motor 45, which may conveniently be mounted in the table structure 31, the motor being drivingly connected with the traction mechanism through speed changing transmission means 46 drivingly interconnected between the motor 45 and one of the shafts 40. The transmission means 46 may be normally arranged to drive the shaft at relatively slow speed when the motor 45 is energized to turn in one direction, suitable gear ratio changing means, controlled as by a solenoid 47, being provided to cause the traction mechanism to be driven at relatively high speed by the motor when the same is energized to turn in the reverse direction.

As shown more particularly in Fig. of the drawings, the driving means may be controlled by a four-pole, double throw switch 48 interconnected as shown with a suitable source 8-8 of electrical power, the contacts of two of the poles of said switch being connected with limit switches 49 and 49'. The contacts and blades of the other two poles of the switch may be arranged as a reversing switch and connected with the motor 45 and with the solenoid 47.

The limit switches 49 and 49 may be mounted in the table structure 31, the same being normally closed switches mounted in position to be opened in response to the arrival of the carriage frame 37 at the limit of its retracting and projecting movement, respectively, in the zones 34 and 35. Accordingly, when the control switch 48 is thrown to its downward position, viewing Fig. 10, the carriage frame 37 being in fully retracted position in the zone 34, the motor 45 will be energized to drive in a direction to move the carriage frame from the zone 34 into the zone 35 at a reduced rate of speed, the switch 49' being then in its normally closed position. When the carriage frame 37 reaches its fully projected position in the zone 35, the switch 49' will open and the motor will stop. After removal of the pan 29 and its contents from the carriage frame, the switch 48 may be thrown to its upward position, viewing Fig. 10, which will cause the motor 45 to operate in a direction to retract the carriage frame to starting position in the zone 34, the switch 49 being then normally closed. Such retracting movement may take place rapidly, since the high speed control solenoid 47 will also be energized during such retractive movement of the carriage frame. When the frame reaches the limit of its retracting m vement, the switch 49 will open and thereby stop the driving motor 45.

After removal of the tray 29 and its contents from the carriage frame 37 in the zone 35, the jig 20 and comb 26, together with the embedded grid strips 19 and the solidified spacing material 50, may be removed from the pan 29. Thereafter, the embedded grid strips and spacing material may be removed from the jig 20 and comb 26 by transversely sawing the same inwardly of the end bars and comb member, which at such time is positioned adjacent one of the end bars. Thereafter, the edges of the screen element may be trimmed, and the diaphragm may be metallic frame 51 around its edges, the finished diaphragm 52 being shown in Fig. 2 of the drawings.

If desired, prior finished by applying a preferably to the application of the edge bind-' 8 ing frame 51, a thin facing sheet or panel 53 may be applied in position covering each of the opposing faces of the diaphragm. Such finishing sheets 53 may comprise any suitable material, such as aluminum, plastic material, or. fiber board, which is substantiallly transparent to X-rays, the purpose of the finishing panels being, of course, to strengthen the structure and to afford protection for the grid strips and spacing material enclosed therebetween.

' It is thought that the invention and its numerous at tendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. The method of making a radiographic diaphragm which consists in mounting and supporting grid strips of X-ray opaque material in spaced and relatively angulated position, submerging the strips in a spacing medium in liquid condition, and then solidifying the medium while simultaneously combing the strips to maintain the same in fiat condition and in accurately spaced and angulated position as the medium solidifies.

2. The method of making a radiographic diaphragm which consists in mounting and supporting grid strips of X-ray opaque material in spaced and relatively angulated position, submerging the strips in a spacing medium in liquid condition, and then solidifying the medium progressively in a direction longitudinally of the strips while combing the strips in the same direction and in advance of the solidification of said medium, to thereby embed and secure the strips accurately in spaced and relatively angulated position in the solidified medium.

3. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, and a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig.

4. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, and means for immersing said jig and comb, together with grid strips mounted thereon, in a bath of strip spacing medium in liquid condition.

5. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for v the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members .and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, means for immersing said jig and comb, together with grid strips mounted thereon, in a bath of strip spacing medium in liquid condition, and means operable to solidify said medium in situ around the strips.

6. Apparatus for making radiographic diaphragms com:

prising a frame forming a jig, providing spaced mounting members having spaced apart,.angulated slots therein.

for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grip strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, tively with respect to the comb in the longitudinal direction of the jig mounted strips, whereby to comb the strips longitudinally as the medium becomes solidified in the pan around the strips.

7. Apparatus for making radiographic diaphragms comproviding spaced mounting prising a frame forming a jig,

and means formoving the pan and jig rela- 9 members having spaced apart, angulated slots thereinfor vable reception of diaphiagmgrid strips, strip i'th correspondingly tion of grid strips'mo'u'nted. in the .jig, a pan sized for the snug reception of ,said ,jig, whereby vto imr nerse ,;strips mounted thereon in 'a'spacin'gmedium in liquid-condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction of jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips.

8. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction of jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips, including means for moving the comb with respect to the pan mounted jig to progress the comb along the jig mounted strips in advance of the solidification of the medium.

9. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction of jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips, including a heater for heating the pan and its contents in the liquid zone.

10. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction of jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips, including means for abstracting heat from the pan and its contents in said solid zone.

11. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction "comprising; a" frame" forming a ;10 .m s -g ngendti ta s s t from said liquid to said so id zone; ig' 'thfelongi tpdinal direction of jig moutifdis'fririsJbIier'by tcmprogressively solidify the ,medium in the pan in the longitudinal direction, of thestrips wherein said traction means comprises, a;pan arriage' movable from 'tl'l'liqui'tLz'one to the lidfzone -and viceiversa.

I l2. .1Ap,paratus for" makingjad iographicftdiaph'ragms gs; prov dingspaced mounting member'shaving'spaced a'p'art, angulated'slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction or jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips, wherein said traction means comprises a pan carriage movable from the liquid zone to the solid zone and vice versa, and driving means operable to travel the carriage at slow speed in one direction and at high speed in the other.

13. Apparatus for making radiographic diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the jig, a pan sized for the snug reception of said jig, whereby to immerse strips mounted thereon in a spacing medium in, liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid Zone, in the longitudinal direction of jig mounted strips, whereby to progress vely solidify the medium in the pan in the longitudinal direction of the strips, wherein said traction means comprises a pan carriage movable from the liquid zone to the solid zone and vice versa, and driving means comprising an electrical motor, transmission means drivingly connecting the motor with the carriage, and motor control means including limit switches operable to stop carriage movement in each direction.

14. Apparatus for making radiograph1c diaphragms comprising a frame forming a jig, providing spaced mounting members having spaced apart, angulated slots therein for the removable reception of diaphragm grid strips, a strip comb movable longitudinally on said frame between said mounting members and formed with correspondingly spaced and angulated combing slots for the accommodation of grid strips mounted in the ig, a pan sized for the snug reception of said jig, whereby to imrnerse strips mounted thereon in a spacing medium in liquid condition in the pan, conditioning mechanism comprising adjacent liquid and solid zones for determining the condition of the medium in the pan, and traction means for moving the pan and jig progressively from said liquid to said solid zone, in the longitudinal direction of jig mounted strips, whereby to progressively solidify the medium in the pan in the longitudinal direction of the strips, wherein said traction means comprises a pan carriage movable from the liquid zone to the solid zone and vice versa, and driving means operable to travel the carriage at slow speed in one direction and at high speed in the other, said driving means comprising an electrical motor, transmission means drivingly connecting the motor with the carriage, motor control means including limit switches operable to stop carriage movement in each direction, and carriage speed changing means operable in accordance with the direction of carriage movement.

(References on following page) 1 1 References Cited in the file of this patent Number UNITED STATES PATENTS Number Name Date 3 5 1,161,193 Cook NOV. 23, 1915 5 1,164,987 Bucky Dec. 21, 1915 1,551,162 Loebell Aug. 25, 1925 1,837,723 McGraw Dec. 22, 1931 43- 2,057,674 Fields Oct. 20, 1936 12 Name Date Wantz et a1. May 3, 1938 Niemann May 10, 1938 Freeman June 28, .1938

OTHER REFERENCES Ser. No. 391,198, Chapuis (A. P 0.), published June 

